1. Field of the Invention
This invention relates to wireless sensing systems. On More specifically, the invention's a wireless sensing system that uses an open-circuit electrically-conductive spiral trace as the system's sensor.
2. Description of the Related Art
wireless sensors and wireless sensor measurement acquisition systems are known in the art. For example, U.S. Pat. Nos. 7,086,593 and 7,159,774 disclose magnetic field response sensors designed as passive inductor-capacitor circuits and passive inductor-capacitor-resistor circuits that produce magnetic field responses whose harmonic frequencies correspond to states of physical properties of interest. A sensor is made by electrically connecting a spiral trace inductor to a capacitor. A magnetic field response recorder wirelessly transmits a time-varying magnetic field that powers each sensor using Faraday induction. Each sensor then electrically oscillates at a resonant frequency that is dependent upon the capacitance, inductance and resistance of each sensor. The frequency, amplitude and bandwidth of this oscillation is wirelessly sensed by the magnetic field response recorder. The sensor's response is indicative of one or more parameters that are to be measured.
While the above-described magnetic field response measurement acquisition system greatly improves the state-of-the-art of wireless sensing, sensor reliability is greatly improved by eliminating their electrical connections. Furthermore, a sensor design that can be readily modified to provide a different response characteristic would be desirable. In this way, sensors could be mass produced in one configuration and then quickly customized by a user for their particular application.